Injection molded paddle blade

ABSTRACT

A paddle blade for use in watersports is provided. The paddle blade includes: a shaft interface portion; a stiffening spine; and a blade portion including a fan-shaped tapered portion, a tip region and blade edges; wherein a hollow region is defined in the blade portion extending through the fan-shaped tapered portion toward the tip region but short of the blade edges.

This application claims the benefit of U.S. provisional patent application No. 60/600,828 filed Aug. 10, 2004 entitled Injection Molded Paddle Blade, which is hereby incorporated by reference in its entirety for all purposes.

TECHNICAL FIELD

The present disclosure relates to a paddle blade for a self-propelled watercraft molded by a gas-assisted injection molding process.

SUMMARY

A paddle blade for use in watersports is provided. The paddle blade includes: a shaft interface portion; a stiffening spine; and a blade portion including a fan-shaped tapered portion, a tip region and blade edges; wherein a hollow region is defined in the blade portion extending through the fan-shaped tapered portion toward the tip region but short of the blade edges.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view of the underside of a first embodiment of a gas assisted injection molded blade for a paddle, showing the hollow region.

FIG. 2 is a side elevation view of the embodiment of FIG. 1.

FIG. 3 is a plan view of the upper side of the embodiment of FIG. 1.

FIG. 4 is a view of the underside of a second embodiment of a gas assisted injection molded blade for a paddle.

FIG. 5 is a side elevation view of the embodiment of FIG. 4.

FIG. 6 is a plan view of the upper side of the embodiment of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present disclosure relates to a novel blade for a paddle for a self-propelled personal watercraft such as a kayak, and a novel paddle having at least one blade. Generally, gas assisted injection molding is used to form a paddle blade (shown at 10 in FIGS. 1-3) having improved buoyancy, stiffness, anti-cavitation characteristics, and other performance features compared to prior paddle blades. In particular, in some embodiments, gas assisted injection molding is used to form a paddle blade with a unique combination of a stiffening spine formed along a first portion of the blade, shown at 12 in FIGS. 1-3, and a fan-shaped extension/taper of the stiffening spine, shown generally at 14, along the remainder of paddle blade 10. Fan-shaped extension/taper 14 allows an area of paddle 10 to include a hollow region 16 with improved buoyancy. Furthermore, fan-shaped extension/taper 14 of stiffening spine 12 acts as a double airfoil, providing lift to aid in the removal of paddle blade 10 from the water and during a paddle stroke.

Careful control of the temperature zones of the injection mold during the injection molding process allows the hollow region to be formed. The outer area of the mold, near a tip region 18 of blade 10, is maintained at a higher temperature than a shaft interface 20 (i.e. where the paddle shaft meets the blade) of the mold so that resin at the tip region of the mold remains at a low enough viscosity for the gas injected into the mold to form a gas bubble near the tip region of the mold. The nominal wall thickness of the paddle (i.e. the thickness between the hollow interior and the exterior) in some embodiments is approximately ⅛ inch, but may be either greater or lesser than this. Furthermore, the walls may be thinner in the tip region 18 of paddle 10 than in other regions.

Paddle blade 10 also is lighter weight than known gas assisted injection molded paddles due to the hollow tip and spine structure. For example, paddle blade 10 has a mass of approximately 300 grams, whereas another gas assisted injection molded paddle blade of a substantially similar size having a solid tip and different stiffening structure than stiffening spine 12 was found to have a mass of approximately 370 grams. Furthermore, paddle blade 10 was found to have a buoyancy of 49 grams, centered about tip region 18, whereas the other blade was found to have a buoyancy of only 11 grams, centered about its shaft interface. Therefore, paddle blade 10 offers superior buoyancy at its tip, thereby offering superior assistance in removing the paddle blade from the water at the end of a stroke.

As shown in FIG. 1, stiffening spine 12 is appears on the back face of the paddle, and in the depicted embodiment extends approximately ⅔ the full length of paddle 10. Hollow spine 12 provides a channel for material and gas flow from shaft interface 20 to tip region 18, and is the primary structure for paddle rigidity, and retention of form. Tip region 18, representing approximately ⅓ of the full length in the depicted embodiment, fans out to meet the blade edges. This results in the unique visual form, provides stiffness to the tip region of paddle 10 and additional structural support to the blade edges. It also results in a hollow region that extends symmetrically through the blade.

The fanned profile of tip region 18 has a section profile described as two opposing airfoils. These airfoils provide lift to the paddle during the paddle stroke, increasing paddle efficiency and reducing user strain. It also provides lift to the paddle as it exits the water, reducing the energy required for the user raise the blade at the end of paddle stroke. This airfoil and lift minimizes splash during entry and exit of paddle into water, reducing incidental wetness of the user. It also provides low resistance of the paddle during entry and exit modes of the paddle stroke, thereby reducing user strain.

The fact that the hollow region 16 extends through stiffening spine 12 and toward tip region 18 results in a paddle blade that is positively buoyant. Buoyancy is centered about tip region 18, which is where buoyancy has the greatest effect on paddle performance. Buoyancy provides upward momentum to the paddle as it exits the water, reducing the energy required for the user to raise the blade at the end of the paddle stroke. Buoyancy counteracts the overall weight of the paddle in use, reducing user strain.

Paddle blade 10 represents an ideal relationship of size and length of the hollow spine, and fan shaped tip, providing a continuous structure for the full length of the paddle blade for retention of form, rigidity in use, and durability. It also results in minimal material usage and overall paddle weight, matching or less than existing designs, while providing the additional maximization of positive buoyancy. Moreover, this design provides minimum cavitation of water throughout the entire stroke. Cavitation severely reduces efficiency during the paddle stroke. Cavitation may be induced in normal use by the articulation of the spine, which in this design is most severe at the shaft and blending into the relatively flat, fan shaped tip profile that has no relative articulation.

In the embodiment of FIGS. 1-3, stiffening spine 12 and fan shaped extension/taper 14 are generously blended into the blade faces and ultimately to tip region 18, resulting in a form devoid of severe articulations. This minimizes cavitation of water throughout the entire stroke, and minimizes cavitation of water during slicing modes of paddle use; i.e., during entry and exit of the paddle into the water, and during bracing and draw strokes.

The embodiment of FIGS. 1-3 further represents an ideal relationship of tip location, power face dihedral, and back face geometry including blade edges, hollow spine, and hollow fan tip. From the end view of the paddle, the relationship of blade edge height, maximum dihedral on the power face, and maximum spine height on the back face minimizes water cavitation during slicing modes of paddle use by allowing positive flow along all surfaces. During modes of paddle use where water pressure is normal to the power face, the dihedral curvature on the power face equally directs water flow from the center line to the edges of the paddle. This effectively stabilizes the paddle as it travels through the water reducing the tendency flutter from side to side which reduces user strain. Cavitation of water is minimized as the flow wraps around the blade edges and meets along the spine on the back face of the blade. During the entire paddle stroke, the tip position and its relation to the paddle blade curvature directs water flow toward the tip of the blade, which results in superior paddle efficiency. It also results in positive water flow toward the tip along all blade surfaces, minimizing the occurrence of water cavitation, and maximizing paddle efficiency. Moreover, the tip position, its relation to the paddle blade curvature, and the power face dihedral results in a rapid shedding of water during the exit mode of the paddle stroke. This minimizes user strain and reduces incidental wetness of user during the paddle stroke.

Embodiment of FIGS. 4-6

Another embodiment of a gas assisted injection molded blade, is shown at 100 in FIGS. 4-6. Therefore, as showing in FIG. 4, a hollow region 116 is shown to extend through stiffening spine 112, fan-shaped extension/taper 114, tip region 118, all the way out to adjacent blade edges 122. In the depicted embodiment, hollow region 116 extends to within one half inch of the blade edges 122, although in the same embodiment it might extend only to within three-quarters of an inch. Corresponding numbers have been used for this embodiment, except that they are in the 100 series. In this second embodiment 100, the entire blade is hollowed by a gas assisted injection molded process. Blade 20 may include stiffening ridges or depressions (not shown) formed along the length or width of the blade to impart greater rigidity to the blade. This paddle blade 100 would increase buoyancy, reduce the occurrence of water cavitation, reduce water splashing and user wetness, on entry and exit. It will also improve paddle stroke efficiency by providing the maximum amount of airfoil lift for the exit portion of the stroke.

Each of the depicted embodiments are designed to be used with a paddle shaft 24 or 124 and paddle handle 26 or 126, although these have only been schematically depicted in the figures.

Variations may be made that will be obvious to those skilled in the art. Such variations are intended to be covered by the claims that follow. 

1. A paddle blade for use in watersports comprising: a shaft interface portion; a stiffening spine; and a blade portion including a fan-shaped tapered portion, a tip region and blade edges; wherein a hollow region is defined in the blade portion extending through the fan-shaped tapered portion toward the tip region but short of the blade edges.
 2. The paddle blade of claim 1 wherein the hollow region extends into the stiffening spine.
 3. The paddle blade of claim 1 wherein the hollow region extends into the tip region.
 4. The paddle blade of claim 2 wherein the hollow region extends into the tip region.
 5. The paddle blade of claim 2 wherein the hollow region is symmetrical within the blade portion and stiffening spine.
 6. A paddle for use in water sports comprising: a paddle handle; a paddle shaft; a shaft interface portion; a stiffening spine; and a blade portion including a fan-shaped tapering portion and blade edges; wherein a hollow region is defined in the stiffening spine and the blade portion extending through the fan-shaped tapered portion toward but short of the blade edges.
 7. The paddle of claim 6 wherein the hollow region extends into close proximity of the blade edges.
 8. The paddle of claim 6 wherein the hollow region extends to within three-quarters of an inch of the blade edges.
 9. The paddle of claim 8 wherein the hollow region extends to within half an inch of the blade edges. 